Since 1993, bison at the Joseph H. Williams Tallgrass Prairie Preserve are gathered to perform various scientific studies and receive vaccinations to ensure the health of the herd. This year, 2,508 bison received a clean bill of health at the 25th annual Bison Roundup.

Consisting of almost 40,000 acres near Pawhuska in Osage County, the Tallgrass Prairie Preserve is the largest protected remnant of tallgrass prairie left in the world!

The roundup, which takes about a week, is the only time the bison are gathered and confined on the prairie. During the roundup, all heifer calves were vaccinated against brucellosis and all keeper animals were vaccinated for several bovine diseases and treated for parasites. For research and record-keeping purposes, each individual bison in the herd is identified with an ear-tag transponder.

A total of 705 bison were sold this year in order to keep the size of the herd within the appropriate ecological stocking rate. Bulls are sold at 6-7 years of age, since after this they tend to become more aggressive and dangerous. Cows are sold at 10-12 years of age. The largest bison that came across the scales at this year’s roundup was a 1,795-lb. bull born in 2010. The infographic below shows this year’s roundup statistics.

The Tallgrass Prairie Preserve bison herd started in 1993 with 300 and reached its target size in 2008 of 2,700 for the summer (includes calves) and 2,100 for the winter (after roundup).

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